Text modified from Abell et al. 2000. Freshwater Ecoregions of North America: A Conservation Assessment. Island Press, Washington, DC, USA.
Major Habitat Type
Xeric freshwaters and endorheic (closed) basins
Drainages flowing into
This ecoregion includes closed drainage systems that do not flow outward into any rivers or oceans.
Main rivers to other water bodies
Large lakes include Goose Lake, which straddles the California-Oregon border, and Lake Abert, Summer Lake, and Harney Lake in Oregon. There are numerous smaller lakes, several of which are far more important to the ecoregion’s biological distinctiveness.
This ecoregion covers inland basins of central-southern Oregon, a small part of northeastern California, and parts of northwestern Nevada. These desert basins are largely defined by alkaline lakes.
The basins of this ecoregion represent an extension of the Basin and Range province that lies between the Cascade Mountains to the west and the Owyhee Upland to the east. The landscape is characterized by a pattern of basins and raised terraces, with uplift areas of grabens and horsts that run in a north-south orientation (Minckley et al. 1986).
The freshwater habitats include alkaline lakes, wetlands, playas, and isolated springs and streams (Anderson et al. 1997).
The dominant vegetation in the ecoregion is sagebrush (Artemisia spp.), typically associated with various wheatgrasses (Agropyron spp.), Idaho fescue (Festuca idahoensis) or other perennial bunchgrasses (Franklin and Dyrness 1988).
Description of endemic fishes
Endemic fish include the Borax Lake chub (Gila boraxobius), a dwarf species found in Borax Lake, Lower Borax Lake, and associated ponds and marshes, and the Warner sucker (Catostomus warnerensis), found in ephemeral lakes, sloughs, lower-gradient streams, and three permanent lakes in the Warner Basin in Oregon and Nevada (Sigler & Sigler 1994; Williams 1995a; Williams 1995b).
Justification for delineation
Ecoregion boundaries are taken from Abell et al. (2000) and are based on subregions defined by Maxwell et al. (1995). Modifications to the boundaries of this ecoregion were based on a biogeographic assessment performed by The Nature Conservancy. The boundaries were modified to include the watersheds of Massacre Lake and Madeline Plains, previously in the Lahontan  ecoregion, as well as Surprise Valley watershed, portions of which were in both the Lahontan  and Sacramento-San Joaquin  ecoregions.
- Williams, J. E. (1995). "Threatened fishes of the world: Gila boraxobius Williams and Bond, 1980 (Cyprinidae)" Environmental Biology of Fishes 43(3) pp. 294.
- Williams, J. E. (1995). "Threatened fishes of the world: Catostomus warnerensis Snyder, 1908 (Catostomidae)" Environmental Biology of Fishes 44 (4) pp. 346.
- Sigler, J. W. and Sigler, W. F. (1994). "Fishes of the Great Basin and Colorado Plateau: Past and present forms" K. T. Harper, L. L. St. Clair, K. H. Thornes and W. M. Hess (Ed.) Natural history of the Colorado Plateau and Great Basin Niwot: University of Colorado Press.
- Frest, T. J.;Johannes, E. J. (1995). "Interior Columbia Basin mollusk species of special concern" Seattle, WA: Deixis.
- Franklin, J. F. (1988). "Pacific Northwest forests" M. G. Barbour and W. D. Billings (Ed.) North American terrestrial vegetation. ( pp. 103-130 ) Cambridge: Cambridge University Press.
- Abell, R.,Olson, D.,Dinerstein, E.,Hurley, P. T.,Diggs, J. T.,Eichbaum, W.,Walters, S.,Wettengel, W.,Allnutt, T.,Loucks, C. J.;Hedao, P. (2000). "Freshwater ecoregions of North America" Washington, D.C.: Island Press.
- Maxwell, J. R., Edwards, C. J., Jensen, M. E., et al. (1995) \A hierarchical framework of aquatic ecological units in North America (Nearctic Zone)\ St. Paul, MN. North Central Forest Experiment Station, USDA Forest Service.
- Anderson, E. W.,M. M. Borman;Krueger, W. C. (1997). "The ecological provinces of Oregon: a treatise on the basic ecological geography of the state"